Process for the preparation of perovskite-based inks

Abstract

A process for preparing a perovskite-based ink, the perovskite having general formulawherein y is between 00.2, including the following steps: (a) dissolving lead iodide (PbI2) in at least one organic solvent, obtaining a first solution;(b) dissolving cesium iodide (CsI) and at least one ammonium salt having general formula:wherein R represents a linear or branched C1-C4 alkyl group, in a part of the first solution, obtaining a second solution;(c) dissolving cesium iodide (CsI) and at least one ammonium salt having general formula:wherein R represents a linear or branched C1-C4 alkyl group, obtaining a third solution;(d) mixing the second solution with the third solution obtaining a perovskite-based ink;wherein in step (d) the molar ratio between the at least one ammonium salt and the at least one ammonium salt is between 0:100 and 50:50.

1 . A process for preparing a perovskite-based ink, said perovskite having general formula (I): 
       
         
           
           
               
               
           
         
       
       wherein y is a number comprised between 0 and 0.2;
 the process including the following steps: 
 (a) dissolving lead iodide (PbI 2 ) in at least one organic solvent selected from dimethyl sulfoxide (DMSO), dimethylformamide (DMF), γ-butyrolactone (GBL), or mixtures thereof, obtaining a first solution; 
 (b) dissolving cesium iodide (CsI) and at least one ammonium salt having general formula (II): 
 
       
         
           
           
               
               
           
         
         
           wherein R represents a linear or branched C 1 -C 4  alkyl group, in a part of said first solution obtained in step (a), obtaining a second solution; 
         
         (c) dissolving cesium iodide (CsI) and at least one ammonium salt having general formula (III): 
       
       
         
           
           
               
               
           
         
         
           wherein R represents a linear or branched C 1 -C 4  alkyl group, in a part of said first solution obtained in step (a), obtaining a third solution; 
         
         (d) mixing said second solution obtained in step (b) with said third solution obtained in step (c), obtaining a perovskite-based ink; 
         wherein in said step (d), the molar ratio between said at least one ammonium salt having general formula (II) and said at least one ammonium salt having general formula (III) is comprised between 0:100 and 50:50. 
       
     
     
         2 . The process for preparing a perovskite-based ink according to  claim 1 , wherein said at least one ammonium salt having general formula (II) is dimethylammonium iodide (DMAI). 
     
     
         3 . The process for preparing a perovskite-based ink according to  claim 1 , wherein said at least one ammonium salt having general formula (III) is dimethylammonium bromide (DMABr). 
     
     
         4 . The process for preparing a perovskite-based ink according to  claim 1 , wherein said step (a) is carried out:
 at a temperature comprised between 30° C. and 80° C.; and/or   for a time comprised between 1 hour and 12 hours.   
     
     
         5 . The process for preparing a perovskite-based ink according to  claim 1 , wherein said step (b) is carried out:
 at a temperature comprised between 15° C. and 35° C.; and/or   for a time comprised between 5 minutes and 2 hours.   
     
     
         6 . The process for preparing a perovskite-based ink according to  claim 1 , wherein said step (c) is carried out:
 at a temperature comprised between 15° C. and 35° C.; and/or   for a time comprised between 5 minutes and 2 hours.   
     
     
         7 . The process for preparing a perovskite-based ink according to  claim 1 , wherein said step (d) is carried out:
 at a temperature comprised between 15° C. and 35° C.; and/or   for a time comprised between 5 minutes and 2 hours.   
     
     
         8 . The process for preparing a perovskite film comprising the following steps: (i) depositing the perovskite-based ink obtained by the process according to  claim 1 , on a substrate to form a film; (ii) subjecting said substrate to thermal treatment (annealing) at a temperature comprised between 120° C. and 190° C. 
     
     
         9 . The process for preparing a perovskite-based photovoltaic cell (or solar cell) comprising the following steps:
 (a 1 ) preparing a glass substrate covered with a transparent and conductive oxide layer (Transparent Conductive Oxide—TCO) (anode);   (b 1 ) depositing a layer based on an electron transport material (Electron Transport Layer—ETL);   (c 1 ) optionally, depositing on the layer based on an electron transport material (Electron Transport Layer—ETL) obtained in said step (b 1 ), a layer based on a mesoporous oxide (scaffold);   (d 1 ) depositing the perovskite-based ink obtained by the process according to  claim 1 , on the layer based on an electron transport material (Electron Transport Layer—ETL) obtained in said step (b 1 ), or on the layer based on a mesoporous oxide (scaffold) obtained in said step (c 1 ), obtaining a photoactive layer;   (e 1 ) depositing a layer based on a hole transport material (Hole Transport Layer—HTL) on the photoactive layer obtained in said step (d 1 );   (f 1 ) depositing a metallic contact (back contact) which constitutes the cathode on the layer based on a hole transport material (Hole Transport Layer—HTL) obtained in said step (e 1 );   wherein said step (d 1 ) is carried out at a temperature comprised between 120° C. and 190° C.